Reconditioning of veneered doors

Most of the apartments in the old blocks had veneered and lacquered doors on the inside. They were simple, made on a wooden frame, with veneered plywood attached to studs, staples or glued to the two sides of the door frame, forming the door faces. Inside were zigzag strips of cardboard, the width of which was equal to the distance between the two plywood boards. The cardboard prevented the doors from warping and the hollow spaces inside provided insulation, thanks to the air that was incorporated. These were called cellular doors. The following is about the renovation of such a door.

How doors are reconditioned depends on the degree of damage. Veneered doors start to look bad because the varnish melts over time from cleaning products and the water it comes into contact with quite often, especially at the bottom (bathroom, kitchen). Over time cracks appear in the film and the water gets to veneerblackening it at first. If no action is taken, the veneer begins to pull away from the door and break.

From the above we see that there are 3 levels of damage:

• the lake has lost its original appearance and lustre;
• the varnish layer is deeply damaged and the veneer has blackened or discoloured;
• the veneer has come loose at the edge, is badly stained, torn or ripped.

Each level has a different remedy. Let's take them one by one.

The lake has lost its original appearance and lustre

Immediately after application, the finish is clean and has a certain shine, a brightness, even if the lake was not very shiny. Over time dirt builds up, the products used for cleaning start to leave marks and the varnish itself "ages" like everything else in this world. Ageing translates into a duller appearance, a decrease in transparency, superficial scratches.

If the veneer has not changed in appearance (darker or lighter spots, chips, cracks), it means that the film has no deep cracks or scratches. If there is discolouration over larger areas, not in the form of spots or streaks, it may be due to light or sunlight affecting only a portion of the door. The defect would require removal of the varnish coat for aesthetic purposes only. If it doesn't bother you, then proceed in the same way as with the aged film.

This means simply washing the veneered door with water and detergent and then wiping it down thoroughly. You can use dishwashing detergent or even soap. After the cleaning, gently sand the entire surface with a fine abrasive sponge or 280 or 320 grit sandpaper. If you want to apply very glossy varnish, use 400-grit sandpaper. Polishing will remove small scratches in the varnish film and help the varnish coat you apply to adhere better. Then apply a coat of nitrocellulose or water-based varnish. They're compatible with most finishes, so you won't have any rejection issues between them.

You'll find both varnish and abrasives or trafalets at DIY stores. Before buying, read labels carefully to make sure it's what you're looking for and to see any hazards. If you're going to use nitrocellulose varnish you'll need a solvent-resistant trowel.

To prolong the life of the varnish you can apply a thin layer of wax. But be careful, wax is the final layer and you cannot apply varnish or any other product over it because it has no adhesion.

The varnish layer is deeply damaged

If the veneer has black spots, streaks, or in some way it is visible that water has reached it, it means that the varnish film is cracked. At this stage you have a choice between two solutions.

The simple solution is to paint the door so that the veneer is no longer visible. Clean and sand the door as above, then apply paint instead of varnish. Pay attention to the compatibility between coats! Try the paint on a more hidden spot first. If when drying it does not crack or "slip" on the lower layer forming craters, then the materials are compatible.

This solution is applied if the veneer is not mouldy. If water has seeped in so that the veneer is blackened from place to place or over larger areas, it has reached the veneer and caused it to mould. In this case the entire finish must be removed down to the veneer. Then sand and treat against mould. After drying, apply 2-3 successive coats of varnish, with drying in between (according to manufacturer's instructions).

Varnish removal is done by sanding or pickling. Pickling products are available in DIY stores. I've worked with Decanol, but there are other brands. The paint stripper is applied with a brush to the entire surface, allowed to work, then the softened lacquer is removed with a squeegee or scraper. Repeat the operation to remove all traces of varnish. Finally, wipe the surface with thinner or technical alcohol

If the varnish layer is removed by sanding, the operation must be done with great care. The veneers are quite thin and the risk of getting plywood is high.

You can treat the veneer against mould with special fungicides or sodium hypochlorite (bleach). Wipe the surface of the veneer with a solution of one part hypochlorite to 2-4 parts water. The wiping cloth should be wrung out well to avoid damaging the adhesive with which the veneer is glued. After the mould has been completely removed, wipe the surface of the veneer several times with a clean, well wrung-out cloth and leave to dry. When completely dry, sand with a medium or fine sponge to smooth the wood grain.

Before applying the finish repair the surface where it is damaged. Plug small holes with putty. Repair is only recommended if the veneer is not badly damaged.

The veneer is blackened in large portions, peeled or/and torn off

When the veneer is peeled, torn or ripped off the edges of the door or there are bumps on the door surface, the film has been so damaged that water has come to affect the adhesive under the veneer. There is also the possibility that the adhesive has "aged", lost its bonding qualities and any knock or mechanical aggression will cause it to detach from the plywood.

Here again we have a simpler and a radical solution, depending on how badly the door is affected. If the swelling is spot on and there is no veneer tear-out, a local repair. Notch the bulge, insert glue with a spatula or spoon tail carefully under the veneer and press. Any excess glue that comes to the surface is immediately wiped off, then a weight is placed on the glued surface. To work fearlessly and leisurely, use aracet adhesivesfor wood. Avoid contact adhesives with immediate cure. They don't give you time to fix any mistakes. Finally, if the film is damaged, protect as above.

If the veneer has pulls, tears and is blackened on the large surface and in depth it must be replaced. It's best to call in a specialist firm that can do it flawlessly. The veneer strips must first be clamped together to form the door leaf which is then glued to the door plywood. In order not to be bottlenecked or swollen, the plywood should be thoroughly cleaned before veneering. You will find information on how to veneer here.

After the new veneer sheet has been laid, the veneered door is sanded and sanded and then the desired finish is applied. like a new door.

I hope I have given the full answer, both to the reader interested in how to save an old door from the 1970s and to others interested in the subject. If you find it interesting, feel free to share. If you have any questions, additions or queries not covered in the article, please leave them in the space below!